In this study, In0.40Mn0.15Co3.85Sb12 was synthesized by the ceramic method, using a traditional melting–annealing treatment (MA), followed by grinding and sintering via the hot-pressing (HP) technique. Rietveld refinement of the powder diffraction (PXRD) data confirms that the resulting phase has a cubic crystal structure in space group Im-3, which is isostructural with the pristine Co4Sb12 phase. The cell parameter a of the filled In0.40Mn0.15Co3.85Sb12 increases after hot pressing compared with the Co4Sb12 phase. This suggests that the partial substitution of cobalt atoms with manganese (Mn) alters the cell size of the resulting material. The PXRD pattern of the In0.40Mn0.15Co3.85Sb12 phase of the MA sample shows a low-intensity line (~30°), which is related to elemental antimony (~4%, by Rietveld refinement). Rietveld refinements support a second model which implies the pressure-induced self-insertion of remanent antimony from the (MA) phase into the void sites after (HP) treatment, leading to a new phase: In0.30Sb0.10Mn0.15Co3.85Sb11.90 (HP). The vibrational Raman modes of the obtained phases, In0.40Mn0.15Co3.85Sb12 (MA and HP), are correlated with those of the pristine phase, Co4Sb12. A strong primary signal at 185 cm−1 in the Raman spectrum of In0.40Mn0.15Co3.85Sb12 (MA) is associated with antimony impurities, which is confirmed by Rietveld refinement. Raman spectra of the HP sample are well correlated to the (SPS) Co4Sb12 phase, which reveals structural changes due to self-insertion of antimony into the voids. The band-gap energy values of both the In0.40Mn0.15Co3.85Sb12 (MA) phase and the (HP) phase are 0.750 ± 0.006 eV and 0.650 ± 0.004 eV, respectively. These values are higher than those of the Co4Sb12 phase, which has a band-gap energy of 0.55 eV. This indicates that the electronic band structure is modified by the partial substitution of cobalt with manganese and the introduction of indium in the icosahedral cages. Electrical transport properties at room temperature show that In0.40Mn0.15Co3.85Sb12 (MA) and In0.30Sb0.10Mn0.15Co3.85Sb11.90 (HP) are n-type semiconductors.

Herein, we present the solid-state synthesis, structural, thermoelectric, and magnetoresistance characterization of Cu[Cr2-xMx]Se-4 selenospinels (x = 0.3 and 0.5; M = Sn, Ti). Powder X-ray diffraction patterns were fitted using the Rietveld method and are consistent with a spinel-type structure ( F(-)d3m space group) and corroborated by Raman spectroscopy and single-crystal X-ray diffraction. The microstructures and morphologies of these systems were examined using high-resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM). The transport properties of all compounds exhibit a decreasing electrical conductivity (20-600 K) and an increasing Seebeck coefficient (300-600 K) as a function of temperature, displaying typical metallic behavior associated with electron scattering by thermal vibrations of the crystal lattice (electron-phonon scattering), which is corroborated by DFT calculations. We determined that the Seebeck coefficient increases from approximately +21 mu V K-1 (250 K) to +43 mu V K-1 (550 K) in CuCr1.5Sn0.5Se4. Additionally, the selenospinels exhibit electrical conductivities (sigma) of similar to 1000-2000 S cm(-1) at 250 K, comparable to that of the CuCr1.2Ti0.8S4 thiospinel. The carrier concentrations (Hall measurements) and Seebeck coefficients are positive, indicating p-type behavior with a hole concentration of similar to 10(19) cm(-3) for all samples at room temperature. Changes in slope are observed for both Sn and Ti selenospinels, indicating two distinct conduction regimes. The thermal conductivity (kappa(tot)) is similar to 3.0 W m(-1) K-1 for Cu[Cr1.7Ti0.3]Se-4 and Cu[Cr2-xSnx]Se-4 samples at room temperature. The lattice thermal conductivity (kappa(latt)) exhibits remarkably low values (similar to 1.5 W K-1 m(-1)) for Cu[Cr2-xSnx]Se-4, reaching levels comparable to those of established high-performance thermoelectric materials, and is lower than those reported for CuTi2S4 spinel at 300 K (similar to 2.5 W K-1 m(-1)). The magnetoresistance reaches a maximum of similar to 40% close to the ferromagnetic/paramagnetic phase transition temperature.

This study reports the synthesis, structural characterization, optical and electrical properties of (Cu2-xAgx)ZnSnSe4 solid solutions. Powder X-ray diffraction patterns and Rietveld refinement results were consistent with phases belonging to the I4 2m space group (stannite-type). The Raman spectra peaks were fitted, displaying the main A2 vibrational mode at about 187 cm−1. FWHM and intensity of the Raman peaks reflect the high crystallinity. Cu1.90Ag0.10ZnSnSe4 and Cu1.80Ag0.20ZnSnSe4 exhibit typical semiconductor p-type behavior with a carrier concentration of + 1019 cm−3. The optical band gaps calculated based on the UV–Vis-NIR spectra were Eg 0.6–0.8 eV.

C25H15NO3, triclinic, P1̄ (no. 2), a = 8.4899(3) Å, b = 10.1383(4) Å, c = 11.3806(5) Å, α = 78.373(1)°, β = 72.020(1)°, γ = 73.381(1)°, V = 885.89(6) Å3, Z = 2, Rgt(F) = 0.0439, wRref(F2) = 0.1290, T = 296.15 K.

Debido a la paralización entre 2020-2021 causada por la pandemia COVID-19, se implementó repentinamente el aprendizaje en modalidad online en todos los niveles de la educación chilena, y en 2022 los establecimientos educacionales volvieron a la modalidad presencial, con preocupación por el rendimiento académico de los estudiantes. La estequiometría es una asignatura compleja de enseñar debido al pensamiento abstracto necesario y, especialmente para los estudiantes de primer año de pregrado, podría ser un desafío debido a que para resolver problemas deben organizar datos y utilizar una secuencia lógica para dar una respuesta correcta. Utilizando una tabla para ordenar los datos y un diagrama de flujo para dar una secuencia lógica de pensamiento apoyamos a los estudiantes de estequiometría en la resolución de problemas con un incremento en su rendimiento académico. Se observó una mejora en el desempeño de resolución de problemas estequiométricos de un 3% a un 58%.

H2 has become one of the most attractive alternatives to replace fossil fuels in clean energy production, but large-scale production remains a challenge. A key step toward this goal is to develop new efficient electrocatalysts for H2 production. This work presents a new mixed metal oxides-decorated CNT paste electrode (MMO@C), which is highly electrocatalytic, for use in the hydrogen evolution reaction (HER). MMO@C is synthesized by a solvothermal method and used as an easy-to-prepare paste electrode. XPS and X-ray analysis indicate that the electrocatalyst corresponds to a mixed surface of Ga2O3-CuO-Cu2O-Cu(OH)2@C. The MMO@C electrocatalyst shows a positive Eo of 0.12 V vs. RHE at −10 mA cm−2 towards the HER in a neutral medium. In neutral and alkaline media, the presence of Ga2O3 facilitates the reduction of CuO to Cu(I) species, which is followed by the formation of Cu(s) active sites. Therefore, the excellent electrocatalytic performance toward the HER in a neutral medium is attributed to the synergistic effect between gallium and copper oxides on the electrode surface. The prominent H2 production using MMO@C electrocatalyst is 1.31 × 10−2 mol cm−2, with a turnover number (TON) of 39,423, a turnover frequency (TOF) of 13,141 h−1, and a faradaic efficiency (FE) of 94.3%. Although the Tafel slope reveals slow reaction kinetics, the outstanding onset potential allows for the coupling of the electrocatalyst to renewable energy production systems, making it an attractive candidate for producing green H2 and for application in membrane water electrolyzers.

Glutathione is a sulfur-containing molecule very interesting to study because it is related to several diseases. Also, it is an electroactive compound, but direct electrochemical studies are complex due to surface electrode passivation, which can be resolved by using modified electrodes. In this work, an electrode based on naphthoquinone (NQ) in a glassy carbon (GC) electrode modified with multi-walled carbon nanotubes (GC/MWCNT@NQ) has been prepared to study the reaction of NQ toward glutathione (GSH) in aqueous medium. A GC electrode was modified with MWCNTs using the drop-casting technique to obtain a GC/MWCNT electrode and subsequently was immersed in a 0.1 mM NQ solution to produce a GC/MWCNT@NQ electrode. The reaction of NQ toward GSH yields an NQ-GSH adduct, which is isolated in GC/MWCNT@NQ-GSH electrode, and shows the same electrochemical behavior as the GC/MWCNT@NQ electrode in phosphate-buffered saline, PBS, at pH 7.44 and, this reaction shows chemical reversibility when the cell contains GSH. The addition of GSH was followed by differential pulse voltammetry technique, showing a good linear tendency, and decreasing in 5% the initial peak current of NQ at 4.98 mu M of GSH

Magnetometry, neutron diffraction experiments, and high-resolution transmission electron microscopy (HRTEM) were performed to study the magnetic behavior of CuCr2-xSnxS2Se2 (0.2 <= x <= 1.0) solid solutions and experimentally determine the appropriate magnetic structure for these systems. For all samples, the main phase with normal spinel-type structure (Fd (3) over barm) was refined. For low Sn concentration a minority monoclinic phase appears also corroborated with HRTEM analyses. Together with the results from magnetization experiments, neutron diffraction measurements allowed to establish that for samples with x <= 0.4 there is a ferromagnetic long-range order at high temperatures labeled with the 3d irrep m Gamma(+)(4) of Fd (3) over barm.1 ', while for x > 0.4 no magnetic signal is observed, indicating that the ferromagnetic behavior is suppressed and replaced with a spin-glass-like state.

Lipoic acid is a naturally occurring compound involved in biological processes with special reactivity due to its 1,2-dithiolane ring. The novel ALA derivatives were synthesized using the Steglich esterification in mild conditions and then concentrated and neutralized with yields of 45.1 to 81.2%.

Herein we report the solid synthesis, structural characterization, magnetic behavior, and electrochemical sensing properties of Mn0.4Cd0.6Cr2S2Se2. Single-crystal X-ray diffraction analysis showed that Mn Mn-0.4 Mn0.4Cd Mn0.4Cd0.6 Mn0.4Cd0.6Cr Mn0.4Cd0.6Cr2 Mn0.4Cd0.6Cr2S Mn0.4Cd0.6Cr2S2 Mn0.4Cd0.6Cr2S2Se Mn0.4Cd0.6Cr2S2Se2 crystallizes in a spinel-type structure. Powder X X-ray diffraction patterns and Rietveld refinement data revealed that this selenide phase is consisted of cubic Fd3m space group. Magnetic field cooling (MFC) measurements indicated an enhancement in ferromagnetic interactions relative to the ferrimagnetic compound Mn Mn-0.4 Mn0.4Cd Mn0.4Cd0.6 Mn0.4Cd0.6Cr2S4, which can be attributed to the substitution of sulphur by selenium. The electrochemical response of modified glassy carbon electrodes with Mn0.4Cd0.6Cr2S2Se2 was increased, the peak current is increased 4-fold, from 20.15 mu A to 83.52 for GC, and GC-Mn0.4Cd0.6Cr2S2Se2 respectively by differential pulse voltammetry, and thus it could be used to design an electrochemical sensor to quantify nitrocompounds, considered pollutants and toxic agents for humans, plants, and animals.

En este estudio se desarrolló una propuesta para enseñar estereoquímica con estudiantes universitarios de la carrera de química y farmacia, con el objetivo de identificar las representaciones de estructuras orgánicas que son más sencillas para el estudiantado utilizando una estrategia didáctica para la identificación, asignación de la configuración absoluta y la comprensión de la estereoquímica en el estudio de la estereoquímica de compuestos orgánicos. Se presentó al estudiantado un esquema con diferentes representaciones y se explicaron las relaciones entre unas y otras, para facilitar la interconversión y que pudieran asignar correctamente las configuraciones de los estereocentros. Se aplicó un pretest previo a la intervención con las proyecciones de Fischer, fórmulas de Haworth, y de cuñas y líneas y conformación silla, mostrando que sólo en las proyecciones de Fischer y en las fórmulas de cuñas y líneas pudieron asignar las configuraciones absolutas de los estereocentros. Sin embargo, después de la intervención, el estudiantado pudo realizar interconversiones en las representaciones de Haworth y silla, aumentando su rendimiento de 0% a 65% y de 0% a 52,5% respectivamente, en el caso de las cuñas y líneas el aumento fue de 22,2% a 60%, y en las representaciones de Fischer de 81,3% a 100%, lo que demuestra que la proyección Fischer era la representación más sencilla para la asignación de la configuración absoluta de los estereocentros.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Neonicotinoid compounds have been used as insecticides since the 1990s to effectively control Hemipteran pests such as aphids, leafhoppers, whiteflies, and additionally, for their lethal activity and low toxicity in humans. The synthesis of novel neonicotinoids compounds was achieved using (S)-(-)-(1-methyl-2pyrrolidinyl)methanol and (+/-)-2-(1-methyl-2-pyrrolidinyl)ethanol with nitrobenzoyl chlorides derivatives in diethyl ether at room temperature to concentrate in vacuum to subsequently neutralize (pH = 8) with 7.4% (w/v) isopropanol HCl solution to obtain hydrochloride salts. (S)-(1-methyl-2-pyrrolidinyl)methyl and (+/-)-2(1-methyl-2-pyrrolidinyl)ethyl 2-nitrobenzoate salts was not possible to form.

Herein, we report the structural characterization and vibrational and physical properties of Cu2ZnSn1−xSixSe4 solid solutions synthesized using the ceramic method. X-ray diffraction analysis and Rietveld analysis of the samples indicated that by increasing the x value from 0 to 0.8, the volume of the unit cell decreased because the ionic radius of silicon is smaller than that of tin. Simultaneously, a phase transition between stannite and wurtz-stannite was observed. The Raman peaks were analyzed by fitting the spectra to identify the vibrational modes by comparison with the experimental data from Cu2ZnSnSe4 and Cu2ZnSiSe4. The spectra of Cu2Zn(Sn1−xSix)Se4 (x = 0.2 and 0.3) show two dominant peaks at approximately 172 and 195 cm−1, which are assigned to the A1 mode of the stannite structure. The optical band gaps for Cu2Zn(Sn0.8Si0.2)Se4 and Cu2Zn(Sn0.2Si0.8)Se4 were 1.30 and 1.74 eV, respectively. These values were intermediate to those of the end members. Electrical properties of Cu2Zn(Sn0.8Si0.2)Se4 revealed p-type conductivity behavior with a carrier concentration of approximately ~+3.50 × 10−19 cm−3 and electrical mobility of 2.64 cm2/V·s.

C10H5NO4, triclinic, P1 ($) over bar (no. 2), alpha = 9.2564(8) A ($) over bar, b = 11.0464(9) A ($) over circle, c = 14.8016(12) ($) over bar, alpha = 110.132( 2)degrees, beta = 106.157( 3)degrees,gamma = 94.770( 3)degrees, V = 1337.7(2) A(3) ($) over circle , Z = 6, R-gt(F) = 0.0567, wR(ref) (F-2) = 0.1797, T = 296.15 K

Herein, we report the synthesis, structural and microstructural characterization, and thermoelectric properties of AgSnm[Sb0.8Bi0.2]Te2+m and Br-doped telluride systems. These compounds were prepared by solid-state reaction at high temperature. Powder X-ray diffraction data reveal that these samples exhibit crystal structures related to the NaCl-type lattice. The microstructures and morphologies are investigated by scanning electron microscopy, energy-dispersive X-ray spectroscopy (EDS), and high-resolution transmission electron microscopy (HRTEM). Positive values of the Seebeck coefficient (S) indicate that the transport properties are dominated by holes. The S of undoped AgSnm[Sb0.8Bi0.2]Te2+m ranges from +40 to 57 μV·K−1. Br-doped samples with m = 2 show S values of +74 μV·K−1 at RT, and the Seebeck coefficient increases almost linearly with increasing temperature. The total thermal conductivity (κtot) monotonically increases with increasing temperature (10–300 K). The κtot values of undoped AgSnm[Sb0.8Bi0.2]Te2+m are ~1.8 W m−1 K−1 (m = 4) and ~1.0 W m−1 K−1 (m = 2) at 300 K. The electrical conductivity (σ) decreases almost linearly with increasing temperature, indicating metal-like behavior. The ZT value increases as a function of temperature. A maximum ZT value of ~0.07 is achieved at room temperature for the Br-doped phase with m = 4.

Compounds of the solid solution series SnTe1–xSex, derived from pristine SnSe and SnTe, are considered as thermoelectric lead-free materials. The crystal structure re-refinement of NaCl-type SnTe0.73 (2)Se0.27 (2) is based on single-crystal X-ray diffraction data and results in higher precision of the bond length [Sn—(Te,Se) = 3.0798 (3) Å] compared to a previous report on basis of powder X-ray data [Krebs & Langner (1964). Z. Anorg. Allg. Chem. 334, 37–49].

Introduction: Due to the confinement of the COVID-19 pandemic, educational centres have remained closed, transferring the teaching process to online mode, thus adapting infrastructure, methodologies, and the university community. Objectives: This work aims to evaluate the effectiveness of strategies in learning organic nomenclature and seek student opinions about committing fraud in organic chemistry course assessments in the online mode in the pharmaceutical career. Methods: The methodologies used allowed the students to understand and apply the organic nomenclature rules, using online collaborative guides and crosswords worked in synchronous classes, previous reading, and the collaborative asynchronous creation of informative files for the recognition of heterocyclic compounds and formative assessment. All assessments were applied in three-people groups in the synchronous classes. Finally, an anonymous survey was administered to know the student perception of the possibility of fraud during the course. Results: A substantial improvement (from 47.7% to 80.5%) was observed in the application of IUPAC rules for organic compounds. Of the students who responded to the anonymous survey, 81% reported that the methodology used decreased the opportunity to commit fraud during assessments.

An entry from the Inorganic Crystal Structure Database, the world’s repository for inorganic crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the joint CCDC and FIZ Karlsruhe Access Structures service and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

A series of CuCr2-xSnxS2.3Se1.7 and CuCr2-xSnxS1.7Se2.3 (x = 0.4, 0.6, and 1.0) compounds were prepared by solid-state reaction at a high temperature. Single-crystal X-ray diffraction analysis showed that CuCr1.1Sn0.9S2.3Se1.7 crystallizes in a spinel-type structure (cubic Fd3¯m space group). The others samples were also consistent with a spinel-type structure but through powder X-ray diffraction patterns and Rietveld refinements. The systems studies showed p-type semiconductor behavior with a carrier concentration per volume of approximately ~+1020 cm−3. The electrical conductivity, σ, showed tin-content dependence. The conductivity of CuCr2-xSnxS1.7Se2.3 increased from ~9.0 to ~17.0 S·cm−1 at room temperature (RT) for x = 0.4 and 0.6, respectively, and the magneto-resistance average value determined for CuCr2-xSnxS2.3Se1.7 and CuCr2-xSnxS1.7Se2.3 was approximately ~10−4 Ω (0.566 T, external magnetic field). DFT calculations revealed that the Cr centers concentrated most of the spin density. A smaller spin polarization featuring the opposite spin was observed for S/Se atoms.